Individuals who suffer degenerative disc disease, natural spine deformations, a herniated disc, spine injuries or other spine disorders may require surgery on the affected region to relieve the individual from pain and prevent further injury to the spine and nerves. Spinal surgery may involve removal of damaged joint tissue, insertion of a tissue implant and/or fixation of two or more adjacent vertebral bodies. The surgical procedure will vary depending on the nature and extent of the injury.
For patients with varying degrees of degenerative disc disease and/or nerve compression with associated lower back pain, spinal fusion surgery, or lumbar arthrodesis (“fusion”) is an effective method and commonly used to treat the degenerative disease. Fusion commonly involves distracting and/or decompressing one or more intervertebral spaces, followed by removing any associated facet joints or discs, and then joining or assistance of an autographed or allographed bone graft. In certain operations, the fusion may also be assisted by a particular spinal implant or one or more bioactive materials.
Fusion of vertebral bodies involves fixation of two or more adjacent vertebrae. This procedure may be performed through introduction of rods or plates, and screws or other devices into a vertebral joint to join various portions of a vertebra to a corresponding portion on an adjacent vertebra. Fusion may occur in the lumbar, interbody or cervical spine region of a patient. A fusion is designed to stop and/or eliminate all motion in the spinal segment by destruction of some or all of the joints in that segment, and further utilizing bone graft material and/or rigid implantable fixation devices for securing the adjacent vertebrae. By eliminating movement, back pain and further degenerative disc disease may be reduced or avoided. Fusion requires tools for accessing the vertebrae and implanting the desired implant, bioactive material, etc. Such procedures often require introduction of additional tools to prepare a site for implantation. These tools may include drills, drill guides, debridement tools, irrigation devices, vises, clamps, cannulae, and other insertion/retraction tools.
Generally, there are five main types of lumbar fusion, including: posterior lumbar fusion (“PLF”), posterior lumbar interbody fusion (“PLIF”), anterior lumbar interbody fusion (“ALIF”), circumferential 360 fusion, and transforaminal lumbar interbody fusion (“TLIF”). A posterior approach is one that accesses the surgical site from the patient's back, and an anterior approach is one that accesses the surgical site from the patient's front or chest. There are similar approaches for fusion in the interbody or cervical spine regions.
Certain procedures are designed to achieve fixation of vertebral bodies, for example, in the cervical spine region, through a midline posterior approach. The main risk of the posterior approach is to the neural elements themselves. These include the nerve roots that are exiting the spinal canal as well as the central grouping of nerve roots called the cauda equine. The implants used in many of these procedures are bulky, over-engineered, or simply not designed for implant in the cervical spine, and therefore increased risk to the neural elements may occur while accessing and during implantation of the device. Should the implant become dislodged, move, or migrate, then those structures are again at risk. Such an approach also is time consuming and increases the hospital stay for the patient. Other risks include insertion and manipulation of the various apparatus required for minimally invasive surgery in this approach, including cannula, curettes, inserters, retractors, etc.
Alternatively, an anterior approach may be used to dissect the damaged joint and implant a fixation device. Many anterior approaches involve wiring the vertebral bodies together. However, anterior approaches are difficult when the patient is a heavy smoker or has hypothyroidism, and the chance of successful fusion decreases as a result.
Other disadvantages of traditional methods of spinal fusion include, for example, the pain associated with the procedure, the length of the procedure, the complexity of implements used to carry out the procedure, the prolonged hospitalization required to manage pain, the risk of infection due to the invasive nature of the procedure, and the possible requirement of a second procedure to remove the implantation device. These and other disadvantages are addressed by the present disclosure in more detail in the Summary and Detailed Description of the Preferred Embodiments, and the appended Claims.